Loud-speaker unit



Sept. 25, 1928.

M. R. HUTCHISON 1 LOUD SPEAKER UNIT Filed Feb. 26, 1927 IN VEN TOR.

r Reese Hufc/Imon.

A TTQRNEY Patented Sept. 25, 1928.

UNITED STATES.

PATENT OFFICE.

MILLER I REESE HUTCHISON, OF LLEWELYN PARK, NEW JERSEY, ASSIGNOB, BY MESNE ASSIGNMENTS, TO ACOUSTIC PRODUCTS COMPANY, OF NEW YORK, N. Y., A

CORPORATION OF DELAWARE.

LOUD-SPEAKER UNIT.

Application filed February 26, 1927. Serial No. 171,350.

. A feature of the invention relates to the provision of a tuned tele hone receiver diaphragm having adjacent t ereto a. resonating column of compressible fluid for reinforcing compressional waves of predetermined fre quency.

A further object of the invention relates to the combination with a tube of restricted diameter having a flare joining the tube to a casing of relatively greater diameter of a 1 tuned diaphragm forming an end wall of the casing and in contact with the compressible fluid defined by the flared tube. According to this feature the fluid within the tube resonates to a predetermined natural fre- 90 quency in consonance with the tuned diaphragm so as to produce greatly amplified effects when the device is actuated at the predetermined frequency.

Another feature of the invention relates to the provision of a stationary electromagnet having aligned solenoids with convergingpole pieces with a metallic element positioned at the conver ence of the pole pieces and a vibratory element joined to the metallic element by means of a link or rod extending between the pole pieces.

Other objects will appear from the follow ing description and claims taken in connection with the accompanying drawing in 6 which there is shown a side elevation, partly in section, of a structure embodying features of the invention.

In thejollowing description and claims,

arts, characteristic features and functions will be identified by specific names for con-' venience of expresion, but they are intended to be as generic in their application to similar or equivalent construction as the art will permit.

Referring to the drawing, there is shown a tube of restricted diameter throughout the main portion of its length and terminating at one end in an enlarged bell 11. At the oppo site end the tube 10 is provided with a flare 12 to the periphery of which there is secured an open ended cylindrical casing 13 having a diameter to conform to the greatest diameter of the flare 121 The casing 13 includes an outer peripheral wall 14, serving as a protective covering. Within the wall 14.- and adjacent to the flare 12 there is provided an annular Washer 15 formed preferably of cork. A relatively thin metal diaphragm 16 is seated on the cork washer 15 and is clamped in place thereon by a second washer 17 also preferably formed of cork. The material of which the washers 15 and 17are formed is of such nature that afl'erbeingcompressed to substa ntially one-eighth of its original thickness, it returns to 0ne-half of that original when the pressure is removed, but retains a remarkable resiliency even under adverse conditions. The washers 15 and 17 are understood to have been so treated and thus serve very efficiently as clamping members for the diaphragm.

The washers are maintained in fixed )osition for so clamping the diaphragm 16 in place by an inner peripheral wall 18 secured to the outer wall 14 and thus forming a part of the casing 13. The walls 14 and 18 are formed of a magnetically inert material such as brass. The diaphragm 16 may be tuned to a predetermined frequency as will appear hereinafter.

Secured to the inner Wall 18 and extending radially inwardly therefrom are spaced magnet cores 20, 20, shown two in number formed of laminations of para-magnetic material, the- -inner end portions thereof being bent into magnets shown 3 in number as at 30, 31, 32. These may preferably take the form of arcuate concentric elements permanently magelectro-magnets 33, 3d are connected in circuit with a source of undulatory energy of audio frequency such as a radio receiving set, a public audio system or a power amplifier, but assuch source forms no. part of t e present invention it is thought that a further description thereof is not required.

The upper end of the casing 13 may be provided with a wall 40 which may be in the form of a sheet of gauze, or there may be provided a tuned chamber or resonator tuned to resonate at the same frequency, to which the born 1, 2 is tuned.

In operation undulatory current of speech frequency is a plied to the magnets 33. 34 and modifies t e pull of the magnetic field upon the armature 21, thus causin movement of the armature in accordance with the signal current impressed upon the magnets. This impresse upon the ma movement is communicated by the link 22 to the diaphragm l6 and thus produces compressional waves in the compressible medium defined b the tube 10. When the ener ets 33, 34, of t e frequency to which the uid within the tube 10 resonates, greatly amplified sounds are emitted from the device.

Thus it will be seen that I have provided 2. In a telephone device, the combination of station'ar electromagnets having alined cores, the en portions thereof being bent into partial convergence, a movable armature positioned adjacent the ends of said cores on one side of the magnet, a diaphragm on the.

opposite side of the magnet and operatively connected to the armature, and tuned to a predetermined natural frequency, and a resonant chamber adjacent said diaphragm for a device for producing compressional waves armature actuated by said magnet, a diaphra tuned to a predetermined f equency and ormingan" end wall of said casing, a tube having a restricted diameter and joined to'the casing by a flare, said tube defining an air column adjacent the diaphragm and tuned to re-enforce the action of t e diaphragm.

4. n aloud speaker a flared tube defining a columnpf compressible fluid resonant to a predetermined natural frequency, a vibratory element positioned on the flare of said tube and having one surface in contact with the fluid within said tube, an electromagnet proximate a differentsurface of said element,

a movable armature controlled by said magnet, and a link operatively interconnecting the armature and the vibrato element.

5'. In a loud speaker, a flare tube defining a column of compressible fluid resonant to a predetermined natural frequency, avibratory element positioned on the flare of said tube and havin one surface in contact with the fluid within said tube, an electromagnet proximate a diflerent surface of said element, said magnet having a pair of spaced pole pieces, a movable armature controlled by said magnet, and a link extending between said pole pieces and operatively interconnecting the armature and the vibrator element.

6. In aloud speaker, a flare tube defining a column of compressible fluid resonant to a predetermined natural frequency, a vibratory element positioned on the flare of said tube and having one surface in contact with the fluid within said tube, said element having a a natural fret uency having a predetermined relation to t e natural frequency of the reso nant fluid column, an electromagnet proximate a difl'erent surface of said element, a movable armature controlled by said magnet, and a link operatively interconnecting the armature and the vibrato element.

7. In a loud speaker. a iiiired tube defining a column of compressible fluid resonant to a predeterminednatural frequency, a vibratory element positioned on the flare of said tube and llflVlIl" one surface in contact with the fluid. within said tube, said element being tuned into consonanoe with the musical note to which the fluid column resonates, an electroma et proximate adifferent surface of said e ement, said magnet having a pair of spaced ole pieces, a movable armature controlled y said magnet, and a link operatively interconnecting the armature and the vibratory element.

8. A sound producer comprising in combination a relatively confined column of atmospheric medium resonant to a predetermined 1,685,086 I I D 3 alined electromagnets, pol'e pieces of "which are surrounded electromagnets.

Signed at New York, in the county of New York and State of New York, this QAth day of February, A. D. 1927.

MILLER REESE HUTGHISON.

y P ent magnets and 

